Response of benthic oxygen demand to particulate organic carbon supply in the deep sea near Bermuda

OVER the past decade an increasing body of evidence has accumulated indicating that much, perhaps most, of the deep sea floor is an environment of substantial temporal variability^1-4. This variability is driven largely by seasonal changes of processes occurring in the surface waters^2,3,5. The coupling of the deep sea floor environment to the surface waters is the result of rapid vertical transport of particulate matter through the water column^6-8, affording only limited time for degradation before arrival at the sea floor. Studies in the Pacific Ocean have indicated that temporal variations in particulate organic carbon fluxes to the sea floor are accompanied by temporal variability in sediment oxygen demand by as much as a factor of four^1,2. We report here time-series studies of oxygen fluxes into the sediments of the oligotrophic Atlantic near Bermuda which contrast sharply with these previous reports. At the Bermuda site, despite large seasonal variations in particulate organic carbon fluxes, in situ measured sediment oxygen consumption does not vary significantly. These results imply that large areas of the sea floor may be characterized by seasonally invariant sediment oxygen demand.